Offshore Joint Seal Unit for Grout-Free Monopile Connections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional grouting mortars in offshore wind energy installations fail to withstand operational loads, leading to joint instability and seawater ingress due to tilting or subsiding of transition pieces relative to monopiles, which compromises the structural integrity and durability of the assembly.
Innovation Solution
A seal arrangement featuring a tapered seal unit, fixed between the monopile and transition piece, utilizing a hollow truncated cone geometry and elastic sealing elements to absorb loads and maintain a stable joint without grouting mortar or mechanical fasteners, allowing for easy assembly and durability under operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional grouting mortar is used to fill the annular gap between monopile and transition piece, then the joint is initially stable, but the grouting mortar breaks under operational loads over time, leading to joint instability and seawater ingress
Solution Approach 1:
A seal unit is installed in the annular gap between the monopile and transition piece before the transition piece is lowered into position. This preliminary sealing action prevents seawater ingress from the outset and distributes operational loads evenly across the joint, eliminating the need for grouting mortar that would otherwise fail under repeated loading cycles
Solution Approach 2:
The seal unit is designed with specific material properties (elastomeric or foam material with appropriate durometer) and geometric parameters (thickness, compression set) that enable it to withstand operational loads while maintaining sealing functionality. The seal unit compresses under the weight of the transition piece to achieve optimal sealing contact and load distribution
2Stability of the object's composition
If grouting mortar is used to enclose the assembly, then encapsulation is achieved, but the mortar cannot counteract fractures caused by operational loads, resulting in tilting and subsiding of the transition piece
Solution Approach 1:
The seal unit is positioned and compressed before the transition piece is fully installed, creating a pre-loaded sealing system that is ready to accommodate operational movements. This preliminary compression establishes optimal contact pressure distribution that prevents tilting and subsiding during operation
Solution Approach 2:
The seal unit is made from flexible elastomeric or foam material that can deform elastically under operational loads, accommodating relative movements between the monopile and transition piece without fracturing. This flexibility maintains encapsulation integrity while absorbing stress that would otherwise cause rigid grouting mortar to fail
3Reliability
If conventional grouting and mechanical fastening methods are used, then joint stability is achieved, but assembly complexity and resource requirements increase
Solution Approach 1:
The seal unit integrates multiple functions (sealing, load bearing, shock absorption) into a single component, eliminating the need for separate grouting mortar and mechanical fasteners. This extraction of essential functions into one element simplifies the assembly process while maintaining joint reliability
Solution Approach 2:
The seal unit serves multiple purposes simultaneously: it seals the annular gap against seawater ingress, distributes and absorbs operational loads, prevents tilting and subsiding, and provides a stable foundation for the transition piece. This multi-functionality reduces the number of components needed while achieving comprehensive joint protection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The seal arrangement provides a durable, load-bearing joint that resists fatigue fractures, maintains encapsulation, and reduces assembly complexity, enabling cost-effective and efficient construction with reduced resource requirements, including the possibility of underwater assembly without diving personnel.
Implementation Method 1
The sealing element is of an elastic design, such that, if the joint elements move relative to each other, it exerts a sufficient compressive force upon an opposite joint surface, and the assembly remains encapsulated.
Implementation Method 2
The conicity makes it possible for (weight) forces to be transmitted in the axial direction.
Data Source
AI summary
Seal arrangement for a joint of two joint elements, in particular realized as a monopile and a transition piece, of an offshore structure, preferably an offshore wind energy installation, in particular a substructure thereof, in which, for the purpose of producing a stable joint, an upper joint element and a lower joint element are inserted into each other in a clamping manner by means of at least one seal unit, comprising one of the joint elements and the at least one seal unit fixed to the joint element, in such a manner that the seal unit, in a joining position, is arranged between an inner joint surface of one joint element and an outer joint surface of the other joint element, at least one seal unit having at least one elastic sealing element, which extends in the circumferential direction around the entire circumference and the thickness (D) of which is greater than the thickness (D′) of an adjoining seal unit region and method for producing a seal arrangement.